"The law of diminishing returns, also known as the law of diminishing marginal productivity, indicates that as one input variable is increased while all other factors are held constant, there will come a point where the increase in output will start to decline."
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Assuming you aren't scammed, it means you typically won't get twice the enjoyment out a $600 an hour appointment as you would from a $300 appointment and even less from a $1,200 one. Basically, you're pay more and more to get proportionately less and less, which is a disincentive for most clients. That being said, there will always be select clients for whom money is no object and willingly pay for the marginal improvements. However, if these clients are few in-between, while there is an abundance of providers, these ladies may be spending most of their time on the bench instead of on the field. In the end, they might make the same amount of income as they would at a lower rate, but they entertain fewer clients, which is a benefit to them. Some ladies may already have another job in which case quoting a higher rate, having limited availability, and receiving fewer responses work out well for them. Regular clients will continue to seek out good value, wherever it may be hiding.

This hobby constantly proves that more $$ is not always better. In fact most of the time, it's not even the tiniest bit better.